Centrifugal switch



Aug. 15, 1950 c. J. WERNER 2,518,584

CENTRIFUGAL SWITCH Filed Jan/l9, 1945 INVENTOR CA1. w/v J. l l/ERNER BY I a fia HIS W ATTORNEYS Patented Aug. 15, 1950 CENTRIFUGAL SWITCH Calvin J. WernenDayton, Ohio, assignortoGeneral Motors Corporation, Detroit,

notationv ofi'Delawal-e Mich, a cor Application Jamar-n9, 1945; SerialN'O. 573,486

V Claims. 1:

This invention relates to improvements in control' devices and particularly such devices which are operated by a centrifugal actuator.

It is among the objects-of the'present invention to provide a centrifugally actuated control device which operates quietlyand over a long period of time without replacement of parts rendered inoperative'due to excessive wear.

A further object of the present invention is toprovide the surface of one metallic member of a mechanism with a glazed, vitreous surface materialwhich provides a smooth and substantially non-abrasive surface over the comparatively rougher surface of the metallic member thereby substantially reducing wear'of' a fibrous 'par-tzof the mechanism which constantly engages said glazed surface with a revolving movement.

Further objects and advantages of: the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodimentof the present invention is clearly shown.

In the drawings:

1. is a. fragmentary sectional view of: an electric motor equipped; with the present invention.v

Figzzi's-a view similarto Fig; 1, certain portions of the mechanism being shown in a. dif-- ferent' position, however;

Fig. 3. is a view taken along: the line 3-3. of Fig. 1.

Fig. 4' is a fragmentary, greatly enlarged sec-- t'iozrof two engaging partsof the mechanism.

Fig.5 is a view similar. to. Fig; 4-, the. one part of; the: mechanism being shown. provided with the present invention.

'Iheswitch of the present invention is identical to the one forming thesubject matter of'the Patent 2,182,977 issued to applicant on December 12. 1.939. and" filed.v October" 23,. 1936,. excepting. however, thatlinith'e present invention the'skilletshaped lever member-".3 is covered with a glazed, vitreous material presenting a smooth and sub' stantially non-abrasive surface: upon. which the fibrous rubbing member constantly, rides.

Referring to the drawingsthe numeral ZDdesignateszthe'field frame-of a motor equipped with the present invention. Av stator comprising a frame 2! and windings 22. and 23 is carried in frame 29. An end cover 24" is secured to the frame 1 20, said end, member rotatably supporting; in a manner not shown, the armature shaft. 25'. which sup-ports the rotor 26 of:the motor.

The shaft 25: has: a transverse opening 2.! throughitsaxiscin-whiclua rodz'28 ofithe centrifugalidevi'ce is slidalolysupported. A collar 29 is secured to the. rod 28 and is normally held. in engagement with the shaft 25 by a coil spring 33 which surrounds the rod 28 on the side of shaft 2 5 opposite the collar 29. Spring 33 is interposed between the shaft 25 and an adjustable nut-34 threaded on one end of the rod 28. A fibrous rubbing collar 32 having a metallic washer of smaller diameter than said collar attached on each side thereof, is mounted on the rod 28 adjacent the collar 29 and several weight members 3 in the form of thick washers are secured on rod 287' and clamped upon the rubbing collar 32 by the head 31! formed at the end of rod 28 oppositethe nut 34.

While the shaft 251s rotating below predetermined speed the spring 33 maintains the rod 28 in the positionin whichits collar 29 is" held upon the shaft 25; However, when the speed of shaft 25 reaches and exceeds this predetermined speed the weight collar-s3! will, due to centrifugal force, move outwardly, thus sliding the rod 28 audits rubbing collar 32 and abutment collar 29' out-'- w-ardly, away from shaft 25 against the efiect of spring 33. Fig. 1 shows the centrifugal mechanisminthe normal positionas the shaft rotates below a predetermined speed and Fig. 2 shows themechanism in the shifted position responsive tothe rotation of shaft 25' at or in excess of the said predetermined speed.

The' switch, actuated by the movementof the rod assembly just described comprises an insulating: plate 36 secured to' the end cover 2! of: the electric motor by studs 31" and 38. Stud 315 has a flanged insulator 31a secured thereto inside'the endcover 24- and likewise stud has aflanged ins lators'ga attached thereto. Two stationary contacts s'and lfi are carried'by the plate136.

The movablemember of the switch comprises a skillet-shaped lever plate 43 having openings for receiving the: insulators 310; and 3'8a respectively. A clearance between each insulator 31a and 3iia.and its respective opening inthe plate 43 is provided so as to permittiltine ofthe plate.

Contacts. 41 and 42' are carried by the plate and are. adapted to cooperate with the stationary con-=- tacts'BQ and 553 respectively to make and break electric" circuits. A spring "48 surrounds their!- sulator 3.1d'and is interposed between the outer flange 31b thereof and the adjacentlever pofi tion. Thisspring exerts a pressure upon the one. end ofithe leveror. plate so that; as shown in Fig; 2, it will'pivoti about its contact M resting upomtheistationarycontact 39 wherebythe 'plate contact 42 is held out of engagement with its stationary contact 40 and the end of the plate opposite the portion thereof engaged by the spring 48 is urged toward and against the rubbing collar 32.

The end of the skillet-shaped plate 43 adjacent the rubbing collar 32 is frusto-conical in shape presenting a sloping surface :35 and a flat surface 46. The surface 45 has an opening 41 greater in diameter than shaft 25 which extends therethrough, thereby permitting free tilting movement of the plate.

When the electric motor is inoperative, or until it reaches a predetermined operating speed, spring 33 will urge the rod 23 to hold its collar 29 upon shaft 25. Under this condition, as shown in Fig. 1, the rubbing block 82 engages the flat surface 46 of the skillet-shaped plate 43, thus urging said plate counterclockwise about the insulating plate and stationary contacts 42 and 40 respectively, acting as pivot. The spring 48 is compressed under these conditions.

When the electric motor reaches the predetermined speed the rod 28 will be moved by weights 3! in response to centrifugal force. As the rod 23 moves so the rubbing collar 32 thereon moves and as said collar moves away from shaft 25 its rubbing contact will move from the flat 46 along the sloping surface as toward its large diameter portion thereby permitting a tilting of the skillet-shaped plate is clockwise by spring 33 first about the pivot formed by engaging contacts 42-463 then when contacts ll-39 engage, contacts 22- 3% will separate and continued tilting clockwise will be effected about the pivot formed by the non-engaging contacts M39.

It will be seen that the dish shaped end or more specifically the flat or the sloping surfaces of said plate t3 is held in constant engagement with the rubbing block or collar 32. While the motor operates said collar is revolved by the rotating shaft 25, thus the rubbing collar in operation engages the plate :33 in a circular rubbing path.

The skillet-shaped plate is is stamped and formed from sheet metal, the surface of which though apparently smooth, presents a microscopically rough and abrasive surface which tests have shown prematurely wears out the fibrous rubbing collar 52 due to its constant rubbing contact with such surface. To avoid this, plates 23 were electroplated as shown in Fig. 4, which is a fragmentary section, on an enlarged scale, of a portion of the plate 33. This figure shows the plated surface covering 5i] assuming practically the same contours of the various irregularities in the surface of the plate and this also presents an abrasive surface which will also cause excessive wear upon the engaging fibrous rubbing collar.

Fig. 5 illustrates a fragment of plate 43 at an enlarged scale, treated according to the present invention. Here the surface of the metal making up the plate has the same irregularities as that shown in Fig. 4. Plating of the surface as shown in Fig. 4 does not eliminate these regularities for the plate-deposit is comparatively thin and follows the contours of the irregularities thus still presenting high and low spots which when engaged by the fibrous rubbing collar causes excessive wear thereof. However, when the metal plate 43 is covered with a glazed, vitreous surface such as porcelain El or the like, the flow, as the covering is applied, fills all of the irregularities and presents a smooth glass-like outer surface which may be slightly wavy but still avoids the presence of the abrasive irregularities as is the case in the electro-plating of the plate 43. The porcelain 5|, flowed onto the plate 43 before subjected to the baking process, fills the recesses 52 in the metal surface, the high spots 53 having a very thin covering of the porcelain. In its fluid state as applied, the porcelain forms a smooth, non-abrasive and glass-like surface which does not cause excessive wear on the constantly engaging rubbing collar 32. In fact tests have proven that a porcelainized plate 43 greatly reduced friction and will cause the rubbing block used with it to far outlast a rubbing block used on a plain or electroplated plate 83. This eliminates replacements and reduces wear of important control parts of the electric motor thereby increasing its eficiency and life.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A control device comprising in combination, a stationary element; a movable member shiftable relatively to said stationary element; an actuator member, constantly engaging the movable member and operative to shift said movable member; means urging the movable member into uninterrupted engagement with the actuator and at a substantially unvarying pressure; a fibrous rubbing block attached to one of said members and constantly engaging the other of said members; a hard and smooth vitreous surface covering on the member constantly engaged by the rubbing block, said surface covering being free from abrasive action on said rubbing block; and means for operating the actuator member.

2. A device in accordance with claim 1, in which the rubbing block is attached to the actuator member and in which the portion of the movable member, constantly engaged by the rubbing block, is provided with a hard and smooth porcelain covering having high wear resisting qualities and which is free from abrasive action on said rubbing block.

3. A centrifugal control device comprising in combination, a control member movable from one position into another to effect control; a spring exerting a substantially unvarying pressure upon the control member constantly urging said control member toward one of its control positions; a, rotatable member; an actuator on the rotatable member, constantly engaging the control member and normally urging said control member toward the other of its control positions against the effect of the spring; and a hard and smooth vitreous covering on the control member, said covering providing a wear resisting surface, free from abrasive action upon the actuator which constantly engages it.

4. A centrifugal control device comprising in combination, a control member tiltable into two separate control positions, said member having a frusto-conically shaped portion; a spring exerting a. substantially unvarying pressure upon the control member constantly urging said member toward one of its control positions; 'a rotatable member; a centrifugal actuator carried'by the rotatable member, said actuator having a fibrous rubbing element in constant engagement with the sloping surface of the frustO-conically shaped portion of said control member and operative to urge said member toward the other of its control positions against the effect of the spring; and a Wear resisting coating of hard, smooth vitreous material on the frusto-conically shaped portion of the control member, said surface being free from abrasive action upon the rubbing, element and having a high wear resisting quality which permits an increased spring pressure to be applied to said control member for effecting more eilicient control.

5. A centrifugal control device comprising in combination, a metallic member tiltable from one position into another to efiect control, said member having a glazed; vitreous coating providing a wear resisting, smooth surface substantially free from abrasive action upon cooperating parts; a centrifugal actuator having a rubbing block in constant engagement with the glazed surface of 6 said member and operative to effect tilting thereof in response to variations in the rotating speed of the actuator; a spring engaging said member and urging it with a substantially unvarying pressure into constant engagement with said rubbing block; and rotatable means supporting said actuator.

CALVIN J. WERNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS u Number Name Date 1,866,481 Norton July 5, 1932 r 2,054,340 Saunders Sept. 15, 1936 2,182,977 Werner Dec. 12, 1939 

